Siddiq is the eldest daughter[9] and second eldest among three children[10] of Shafiq Siddiq,[11][2] who was an academic and university economics professor[1] before a stroke left him disabled,[6] and Sheikh Rehana,[9] who gained political asylum in the UK as a teenager.[6] They met when Shafiq Siddiq was studying for a PhD[12] and they married in Kilburn in 1970. Her maternal grandfather is Sheikh Mujibur Rahman, founding father and the first President of Bangladesh.[13] Her mother's elder sister is Prime Minister of Bangladesh Sheikh Hasina.[14][15] She has an elder brother, Radwan "Bobby" Mujib[16][13] (who lives in Bangladesh),[17] and a younger sister, Rupi.[18]

In a 2006 by-election, Siddiq stood for Camden Council but did not win; it was a safe Liberal Democrat seat which had been held by them for 25 years.[1] In May 2010, in the Camden election, Siddiq became the first Bengali female councillor in Camden Council,[21] where she was Cabinet Member for Culture and Communities until May 2014.[22]

During 2013 and 2014, after being selected as Labour candidate, she campaigned on various topics, including against the proposed high-speed railway expansion High Speed 2,[31] and in opposition to high pay day lender charges on Kilburn High Road.[23] She has also campaigned in support of local services, such as to keep Belsize Fire Station open,[32] to improve disabled access at West Hampstead tube station[33] and to save the Swiss Cottage post office.[34]

In the 2015 general election, Siddiq won the Hampstead and Kilburn seat with 23,977 votes, with a turnout of 67.3%.[35][36] The seat was previously held by Glenda Jackson.[37] The seat had previously been the second tightest in the country after Jackson retained the seat by just 42 votes in 2010[38] and was billed in 2015 as the UK's most marginal general election contest.[39]

In November 2015, she campaigned against changes to junior doctor contracts.[52] In the same month, Siddiq's maiden speech in Parliament was judged one of the top seven from 2015's intake of MPs by the BBC.[53]

In August 2017, Siddiq called for businesses to "address imbalance" in the employment of BAME individuals to improve the diversity of its workforce.[64]

In September 2017, Siddiq was appointed as Chair of the new Childcare and Early Education All-Party Parliamentary Group (APPG).[65] In the same month, Siddiq wrote to the Home Office to ask for children's passports to be amended to contain both their parents' names to avoid confusion at airports and borders. Siddiq had been stopped with her daughter at UK border control whilst returning from a family holiday until her husband joined them, because she did not have the same surname in her passport as her child.[66][67][68]

In November 2017, whilst campaigning for the release of her constituent, the British-Iranian citizen Nazanin Zaghari-Ratcliffe, who is detained in Iran, she was asked by Alex Thomson of Channel 4 News and ITN about using her family ties to the Bangladeshi government, led by her aunt, in order to liberate British Bangladeshi barrister Ahmad bin Quasem, who is thought to have been abducted by state security forces in Bangladesh. The programme's editor, Ben de Pear, complained about Siddiq's "threatening behaviour" to a pregnant producer, while Siddiq complained to the police about her interlocutors.[69][70][71] She later apologised in a statement to the producer, Daisy Ayliffe, for the offence caused.[70]

In May 2018, Siddiq supported an equal pay campaign aimed at building pressure on employers.[72] In the same month, Siddiq described the actions of the Israeli military during demonstrations on the Gaza border as "unjustified" and "inhumane". She said: "I condemn without reservation these violations of international law and human rights by Israel... The protest has been twofold - to highlight the shocking conditions which Palestinians are forced to live in and to demand their right to return to their homes..."[73]

In August 2018, Tulip Siddiq joined international calls for her aunt's government to release Bangladeshi photographer Shahidul Alam, who had been jailed after reporting about protests by schoolchildren over road safety problems, and had subsequent stated he was tortured.[74][75]

Siddiq was a board member of West Euston Partnership and is governor of the Camden and Islington NHS Foundation Trust.[14] She served as national BAME (Black, Asian and Minority Ethnic) Officer for Young Labour and Women's Officer for London Young Labour. She is an executive board member of Unite the Union, a member of the Co-operative Party, a fellow of the Royal Society of Arts and is also a member of the Commonwealth Journalists Association (UK).[7] In July 2011, she joined Brunswick Group LLP as an Account Director. She also oversaw Camden's engagement with the 2012 London Olympics, which saw the launch of three legacy schemes to encourage more physical activities, Camden Sports Academy, School and Community Games, and Pro-Active Ambassadors.[76]

Siddiq served two years as a school governor at Beckford Primary School and Richard Cobden Primary School[77] and is a current governor at the Working Men's College in Camden.[78] As of January 2014, Siddiq supports a number of organisations in Hampstead and Kilburn, including school governor roles at Emmanuel Primary School[79] and Granville Plus Nursery[80] as well as being a trustee of the Camden Arts Centre.[81] She has also written for Hampstead and Highgate Express[7] as a foreign correspondent, primarily covering the U.S. elections.

Siddiq is a Muslim[15] but said she is "more cultural than religious".[5] Siddiq's father suffered a stroke, which left him disabled[6] and unable to speak for five years;[12] he now uses a wheelchair.[6] She has cited the NHS and the care her disabled father received as the reason why she joined the Labour Party.[23] She has identified Barbara Castle as her political heroine.[1] Siddiq has described her mother and maternal aunt as "two very strong feminists".[85]

In 2013,[86] Siddiq married Christian William St John Percy (born 1984),[87] who is a Cambridge-educated[88] company director[89] and strategy consultant with a background in the British civil service.[88] The wedding reception was held a few months later on 7 July[10] in West Ham, London.[90] Siddiq lives in a flat on Finchley Road,[36]West Hampstead, London with her husband.[23][25][91] In November 2015, it was confirmed Siddiq was five months pregnant and expecting a daughter[92] in April 2016.[93] In April 2016, Siddiq gave birth to a daughter at the Royal Free Hospital in Hampstead.[94][95][96][97][98] Siddiq returned to work nine weeks after an emergency caesarean section,[99] after a 40-hour long labour after which she caught an infection and so did her child. Siddiq later developed a serious case of mastitis because she was overworked and exhausted from going back to work early.[100]

She gave birth to a second child, a son, by a planned caesarean section in January 2019.[101] Two days before the birth she attended the Commons in a wheelchair, for a critical Brexit-related vote.[101] On 29 January, following a constitutional change, she became the first ever MP to vote by proxy.[102]

Siddiq's daughter attends a Jewish nursery. Since becoming an MP, Siddiq has spoken at Limmud and attends synagogue events.[103]